Field Open Channel Flow Measurement

It is usually recommended to use the flow area method to measure the flow of open channels after the on-site inspection.

An ultrasonic level meter measures the liquid level and an electromagnetic flow meter measures the flow rate.

An open channel flowmeter consists of an electromagnetic flowmeter, a flow indicator and an ultrasonic level transmitter.

The electromagnetic flow meter is established in the channel, and converts the water flow speed into an electrical signal and transfers it to the display via a cable. The ultrasonic level transmitter is established above the channel close to the flow meter, measures the depth of the water level above the cross-section of the channel, and transmits it to the display with a 4 to 20mA signal. The display instrument calculates the water flow rate of the cross-section thru the flow velocity signal, water level signal, and several channel parameters.

According to the multi-point technique of open channel flow measurement standards, the influence of flow velocity measurement errors resulting from flow changes on flow may be randomly corrected.

To enhance the measurement accuracy, the electromagnetic flow meter is implemented to measure the channel flow velocity, the flow rate is calculated by the liquid level and flow velocity.

This system is equipped with a wireless communication remote monitoring terminal to collect the physical quantity of multi-channel and multi-parameter quantity. In addition, the system uses a public mobile network to upload data to the cloud, is lightning-proof and waterproof, and is battery-powered. Data can be traced via a mobile phone or a computer.

Flowmeter installation:

The flowmeter is installed on the sidewall of the canal (if there is no sedimentation problem, it can be installed at the bottom of the canal).

The direction indicator points downstream of the water flow, making sure that the flow meter is parallel to the water flow axis.

Level transmitter installation:

The ultrasonic level transmitter must be applied as near as possible to the installation position of the electromagnetic flowmeter. It shall be perpendicular to the water surface. The distance from the port plane of the ultrasonic level transmitter to the bottom of the channel is somehow larger than its real range. Waveguides must be installed if there is litter, refuse, air bubbles, or large fluctuations in the water. The diameter of the waveguide should be more than 120mm and there must be no joints.